(a) Field of the Invention
The present invention relates to a liquid crystal display and a driving method thereof, and particularly to a liquid crystal display having a plurality of gray voltages with varying magnitudes and a driving method thereof.
(b) Description of the Related Art
A typical liquid crystal display (“LCD”) includes a pair of panels with field-generating electrodes and a liquid crystal layer with dielectric anisotropy interposed therebetween. The liquid crystal layer is applied with electric field generated by the field-generating electrodes, and the transmittance of light passing through the liquid crystal layer is adjusted by controlling the magnitudes of voltages applied to the field-generating electrodes, thereby obtaining desired images.
Generally, a dark image of a display is much unclear at a bright place than at a dark place. This is because human eyes hardly recognize the brightness difference between portions of a dark image at a bright place. Since the brightness difference between low grays of a conventional LCD is small, the visibility of LCD images, specifically for a motion picture, is inferior to that of other kinds of displays.
In order to improve brightness difference between low grays, it is suggested to improve a light source of an LCD such as a backlight unit. For example, the light intensity of lamps of the backlight unit is increased, the number of the lamps is increased, or several various prism sheets are provided in the backlight unit. However, these increase the power consumption, the weight and the cost of the LCD.
In addition, it is hard to increase the light intensity of the backlight unit twice, three times or more than the normal intensity, and even though the intensity would increase, the visibility is not so much improved in comparison with the increasing rate of the intensity of the backlight unit. Furthermore, a bright screen makes users feel fatigue soon.